Bag making method and bag making apparatus

Abstract

The product efficiency of bags each with an end face part is increased. A panel webs is guided to be divided along a line of weakness of the panel web and to be folded along division edges of the panel web. This guiding of the first panel and temporary sealed sections cause a side gusset to be cut open along a line of weakness of the side gusset such that open surfaces are formed. After the forming of the open surfaces, an end face web is supplied to be superposed on folded parts of the panel web and the open surfaces of the side gusset.

What is claimed is: 
     
       1. An apparatus for making plastic bags, the apparatus comprising:
 a panel web feed device superposes a first panel web and a second panel web on each other and feeds the first and second panel webs in a longitudinal direction of the first and second panel webs; 
 a side gusset supply device supplies a side gusset to the first or second panel web to dispose the side gusset in a width direction of the first and second panel webs before superposing of the first and second panel webs, wherein the side gusset is interposed between the first and second panel webs when the first and second panel webs are superposed on each other, the side gusset being folded in halves on opposite sides with respect to a longitudinal centerline thereof; 
 a line-of-weakness forming device disposed downstream of a position where the panel web feed device superposes the first and second webs on each other, to form a first line of perforations in the first panel and a second line of perforations in the side gusset, the first line of perforations extending in the longitudinal direction of the first and second panel webs, the second line of perforations extending in a width direction of the side gusset and aligned with the first line of weakness; 
 a temporary seal device seals the side gusset to the first and second panel webs so as to form temporary sealed sections after the superposing of the first and second panel webs; 
 a first guide device guides the first panel web as the first and second panel webs are fed to divide the first panel web along the first line of perforations to fold the first panel web on sides of division edges of the first panel web along fold lines, and to cut the side gusset open along the second line of perforations for forming open surfaces, the fold lines extending in the longitudinal direction of the first and second panel webs; and 
 an end face web supply device supplies an end face web to the first panel web as the first and second panel webs are fed to superpose the end face web on folded parts of the first panel web and the open surfaces in the longitudinal direction of the first and second panel webs, 
 the line-of-weakness forming device comprising:
 an arm supported at one end thereof to be pivotable around a pivot shaft extending in the width direction of the first and second panel webs; 
 a disk-shaped perforation cutter for forming the first and second lines of perforations, wherein the disk-shaped perforation cutter includes a rotation shaft extending in the width direction of the first and second panel webs, and is supported by the arm to be rotatable around the rotation shaft; 
 a biasing member disposed to bias the arm in a direction in which the disk-shaped perforation cutter is away from a feed plane of the first and second panel webs; and 
 an adjustment member allows adjustment of cutting depth of the disk-shaped perforation cutter into the first panel web and the side gusset, wherein the adjust member is in contact with the arm to prevent the arm from being moved around the pivot shaft by the biasing member. 
 
 
     
     
       2. The apparatus of  claim 1 , wherein the biasing member is a spring. 
     
     
       3. The apparatus of  claim 1 , wherein the adjustment member is rotatably supported around an axis thereof by a support member, and wherein the adjustment member is movable with respect to the support member in a direction toward or away from the arm upon rotation around the axis. 
     
     
       4. The apparatus of  claim 3 , wherein the adjustment member is coupled to the support member via screw engagement. 
     
     
       5. The apparatus of  claim 4 , wherein the adjustment member is an adjustment knob.